Just need a simple domain availability check that uses AJAX to display the results after pressing 'Check' without the page reloading. User will input the SLD and the TLD will be selected from a drop down box.
The script will have a non-js backup, i.e. page will reload and show results for non-js users.
If domain is available to register the relevant WHMCS order link will be generated by passing the SLD and TLD to a url like below
[url removed, login to view]